Pneumatic external draw lapping head



July 15, 1952 BRANDT 2,603,044

PNEUMATIC EXTERNAL; DRAW LAPPING HEAD Filed March 21, 1951 3 Sheets-Sheet l grwcmfm Emil H Brandi July 15, 1952 E. H. BRANDT PNEUMATIC EXTERNAL DRAW LAPi ING HEAD 3 Sheos-Sheet 2 Filed March 21, 1951 24 grwc/wto'v la Em-il J-LEbrand-l: v I

awn/wags July 15, 1952 E. H. BRANDT PNEUMATIC EXTERNAL DRAW LAPPING HEAD 3 Sheets-Sheet 3 Filed March 21, 1951 abbowugs Patented July 15, 1952 PNEUMATIC EXTERNAL DRAW LAPPING HEAD Emil H. Brandt, Davenport, Iowa Application March 21, 1951, Serial N 0. 216,824

3 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention described in the specification and claims may be manufactured and used by or for the Government for governmental purposes without the payment to me of. any royalty there- This invention relates to the art of honing or abrading and in particular to devices of the type known as lapping machines.

It is the primary object of this invention to produce a new and improved external polishing head for use on a Barnes draw lapping machine. The Barnes machine referred to herein is a device for abrading cylindrical objects in which the cylinders are held horizontally and turned by the machine structure. A non-rotating abrading head is mounted so that it can be moved along the axis of the machine at the will of an operator. The cylinders are inserted within the head i piece may be treated at one time than is treated now, with consequent saving of time.

Another disadvantage of the present heads is that they depend for the pressure applied to the stones upon springs and wing nuts which can be controlled only by hand and at best with some difliculty. Another object of the invention therefore is to provide a device of the character described controlled more easily than through wing nuts and springs operated by hand. Compressed air is actually the medium of control chosen for my invention.

Another disadvantage of the heads in use now is that removal and replacement of the grinding stones is a rather difiicult operation, requiring that the entire upper half of the lapping head be removed. It is consequently still another object of the invention to provide a lapping head which permits the abrading stones to be easily and individually removed and replaced.

Other objects of the invention will be evident from the following description and the appended drawings in which:

Fig. 1 is an end elevation of my new lapping head;

Fig. 2 is a sectional view along line 22 of Fig. 1;

Fig. 3 is a section taken along the line 3-3 of Fig. 2; I

Fig. 4 is a side elevation of the new lapping head; and

Fig. 5 is a detailed drawing of one section of my apparatus showing a second embodiment.

Described briefly, my invention consists essentially of a hollow relatively long retaining cylinder adapted to fit around a cylindrical workpiece held in the Barnes machine. symmetrically positioned above this retaining cylinder are two pneumatic cylinders, each actuating a lazy tongs. Upon the retaining cylinder are mounted two collars which have a limited sliding movement upon the cylinder. The collars are controlled by the free ends of the lazy tongs. Within the retaining cylinder are positioned abrading stones held in.place by detachable springs. Movable keys contact the stones and extend through the retaining cylinder. The movable keys make external contact with bevels in the slidable collars. Consequently motion of the collars, caused by the lazy tongs and the pneumatic control of the tongs, is transmitted to the abrading stones. in opposition to the force of the positioning springs. Any desired pressure can thus be applied very simply to the stones.

Referring now more particularly to the drawings, a workpiece I0 is shown engaged in a retaim'ng cylinder l2 by abrading stones l4 set in backing plates l6. Eight such backing plates are evident in the embodiment of the invention illustrated but a greater or lesser number may be used as desired. The backing supports are held tightly against the interior surface of the cylinder [2 my means of detachable springs [8 attached to pins 20 embedded in the cylinder and the reinforcing annuli 22, at the ends of the cylinder. Springs [8 fit into slots l 9 cut into the backing plates. Each backing plate carries two abrading stones l4, one at each of its ends. Behind each abrading stone and contacting the backing plate of the stone is a key 24 slidably mounted in a key-way 26 in the ring 28. The rings 28 are mounted in the retaining cylinder [2. The cylinder itself is positioned on the Barnes machine through supports [3.

'Slidably held at opposite ends of the retainer cylinder are annular collars 30 and 32. These collars contain bevels 34 on their interior faces contacting the sliding keys 24 and constitute adjusting or control means for the keys. Each bevel is so constructed that it slopes outward towards the end of the retaining cylinder l2 closest its respective collar. Each of the collars bears two free end of bar 42 is connected through trunnion 36 to collar 38. The free end of the other collar 32. The shorter bars 46 and 48 are pivoted together at one of their ends bya pivot l5 located half Way along the length of the retaining cylinder 12. The free end of bar 46 is pivoted at a point 41 about halfway along bar A2 while the free end of bar 48 is in the same manner pivoted at point 49 to bar 46. While only lazy-tongs 40 has been described, lazy tongs 4| isof' identical construction with connections on the collars 30 and 32 and the cylinder [2 diametrically opposite the connections of tongs 49. However while lazy tongs 49 is. pivoted at fork 5'4,-'lazy tongs 4| is pivoted at fork 55. The two tongs of course parallel each other along opposite. sides of the cylinder l 2.

Thetwo forks Stand 55 are connected through piston rods 52 and 53 .to small conventional pneu- .Standard 66 is mounted rigidly on cylinder l2 .and consequently holds the pneumatic cylinders .in proper fixed positions relative to the other .parts of .the apparatus. 1

Various modifications lie within. the scope of ,my invention. Figure 5 shows one such, modification in which the sliding key 24 is .made integral withthe stone backing support 16. In this embodiment the springs 18 are relieved of somestrain in that the keys now give longitudinal support to the backing plates.

The operation of the device .is obvious from the description. The new and improved abrading head islsubstitutedon the lapping machine for. the hand'controlled head now in. use. A

workpiece-is rotatably mounted inQthisLhea-d and the abrading operation is carried out as normally performed As far as the head itself is concerned, an operator merely controls. by hand the pressure on the pneumatic cylinder from a valve not shown in the drawings. pressure is transmitted through the lazy tongs to the movable collars and the slidingkeys which actuate the grindingstones, the (jamming-action of the'bevels changing thev longitudinal motion of the collars-a radial movement of the-keys. Increasing the pressure in the pneumatic cylinders opens the pair of lazy tongs, drives the bevels outward, and throughthe keys increases the pressure on. the stones. Removal of pres- .sure. on the keys permits the restoring force of the springs holding the hacking plates to operate. The pressure applied to the stones can consequently belregulated within desired limits.

The. stones are very easilyremoved from or replaced, in'my lapping head. It is only neces- The piston 10 long bar, 4-4, is in similar fashion connected to sary to loosen the tension on the retaining springs or slip the spring out on its slot and over the end of the backing plates. One or more plates can be replaced at a time without taking the entire head to pieces. The objects of the invention have therefore been achieved by the device described. I do not-however. desire to be bound strictly by this description but solely by the scope of the appended claims.

I claim:

'1'. A lapping head for abrading a cylindrical work-piece comprising a hollow retaining cylinder carrying internally abrading means adapted to engage said work-piece, springs resiliently holding said abrading means within said cylinder, keys slidably extending through key-ways in the cylinder and making contact with the abrading means, said key-ways being spaced in two groups circularly around the circumference of said cylinder, one of said groups being located a predetermined distance from one end of said cylinder and the other of said groups being located the same predetermined distance from the other end of said cylinder, a slidable annular collar around each of said key-ways, a bevel on the inner surface of each annular collar making slidable angular contact with the keys extending through said key-ways, two lazy tongs extending parallel to each other lengthwise along the sides of the cylinder. pivotally connected to-said cylinder and attached to the collars at points thereon diametrically opposite each other, each of said lazy tongs consisting of two relatively longer bars, pivoted at a junction at one of their respective ends and pivoted separately to one of the collars .at the other of their ends, and of two relatively shorter bars, pivoted together to thecylinder at one of their respective ends and pivotally connected separately 'at'th'e other of their ends tov corresponding points along the lengtho'f the relatively longer bars, and means for impartingrectilinear motion the junction point of the two relatively longer bars in a direction perpendicular to the axis of said retaining cylinder whereby, through the action of the lazy tongs, the annular collars are slidably moved in opposite directions along the'cylin der in such a manner as to urge, through the sliding keys, the abrading means against the springs when the collars moving towards the respectively nearer ends of said cylinder.

2. The lapping head of claim 1 in which the means for imparting rectilinear motion to the junction point-of the relatively longer bars is a hand-controlled hydraulic piston.

3. The lapping head of claim 2 possessing a separate hydraulic piston for each lazy tongs, the two pistons being synchronously controlled to ensure cooperative action of the two lazy tongs.

EMIL H. BRANDT.

1 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

